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Infrastructure and the Need for Condition Assessment
Published in Justin Starr, Water and Wastewater Pipeline Assessment Technologies, 2021
The first phase of corrosion in concrete pipes is strictly chemical. The surface of a newly installed pipe (or indeed, any concrete structure) has a pH that is too high for any effective bacterial growth to take place. Naturally occurring bacteria (such as Desulfovibrio desulfuricans) in the wastewater stream break down sulfates and organic matter in order to release carbon dioxide and hydrogen sulfide gases. These gases diffuse into pores in the concrete structure. If moisture content is high, this can lead to the aqueous production of weak acids, which then react with underlying minerals like calcium hydroxide. It is important to know that this stage of corrosion does not actually lead to wall loss – instead, this process neutralizes the surface of the concrete, reducing the pH over the course of a few months.
Microbiological Aspects
Published in Héctor A. Videla, Manual of Biocorrosion, 2018
Diverse species of SRB like Desulfovibrio vulgaris or Desulfovibrio desulfuricans can use hydrogen oxidation as an energy source for growth. The active growth of SRB requires reduction conditions in the medium generally more severe than those attained by deaeration. Generally, it is assumed that a redox potential lower than -100 mV (vs. normal hydrogen electrode) is needed to allow a suitable growth. The environmental conditions in restricted areas of solid/liquid interfaces can be appropriate for SRB growth due to reducing conditions created by biogenic hydrogen sulfide or to the presence of aerobic bacteria that actively consume the oxygen of the medium, for instance, when microbial consortia are located within the thickness of biofilms.
Sustainable Bioremediation Strategies to Manage Environmental Pollutants
Published in Maulin P. Shah, Removal of Refractory Pollutants from Wastewater Treatment Plants, 2021
Prasenjit Debbarma, Divya Joshi, Damini Maithani, Hemant Dasila, Deep Chandra Suyal, Saurabh Kumar, Ravindra Soni
Microorganisms are also capable of heavy metal removal by either using them as electron acceptors or remediating them from the environment via bioabsorption or bioaccumulation. Desulfovibrio desulfuricans converts soluble heavy metals such as cadmium and zinc to insoluble metal sulphides, thus reducing their bioavailability in nature. Microbial cell surfaces contain various negatively charged functional groups that offer active binding sites for positively charged heavy metal ions; thus, microbial biomass is a useful biosorbent for heavy metals [22]. Bacterial strains reported in the bioremediation of heavy metals include Pseudomonas aeruginosa, Enterobacter A47, Sphingomonas paucimobilis, Azotobactervinelandii, Pasteurella multocida, Pseudomonas oleovorans, Xanthomonas campestris, Bacillus cereus, Kocuria flava, Sporosarcina ginsengisoli, Pseudomonas veronii, Pseudomonas putida, Enterobacter cloacae, and Bacillus subtilis [30,31]. Through the process of co-metabolism, microorganisms are able to degrade to harmless end products, thereby remedying or eliminating hazardous substances found in polluted environments. Bacterial consortiums have been reported to be more efficient in the removal of heavy metals than single strains. For instance, a bacterial consortium consisting of Viridibacillus arenosi B-21, Sporosarcina soli B-22, Enterobacter cloacae KJ-46, and E. cloacae KJ-47 was reported to remediate heavy metal contamination from the soil with greater efficiency in comparison to using a single strain [32]. Some genetically modified strains such as Escherichia coli strain M109, Deinococcus geothemalis, Cupriavidus metallidurans, and Pseudomonas spp. have been engineered for the effective decontamination of heavy metal polluted sites [22]. Many bacterial strains have been reported in radioactive waste management such as Rhodococcus sp., Deinococcus radiodurans, Nocardia sp., Pseudomonas putida, Shewanella putrefaciens CN32, Desulfosporosinus spp., Anaeromyxobacter, Geobacter species, D. desulfuricans G20, Geobacter sulfurreducens, and Arthrobacter ilicis [33].
Optimization Study of Nickel and Copper Bioremediation by Microbacterium oxydans Strain CM3 and CM7
Published in Soil and Sediment Contamination: An International Journal, 2020
Parviz Heidari, Faezeh Mazloomi, Samaneh Sanaeizade
In previous studies, the different strains of bacteria and fungi have been identified to be used in Cu and Ni bioremediation, such as Bacillus thuringiensis KUNi1 (Das, Sinha, and Mukherjee 2014), Desulfovibrio desulfuricans (Kim et al. 2015), Candida sp. (Dönmez and Aksu 2001), Rhizopus arrhizus (Preetha and Viruthagiri 2007), Stenotrophomonas maltophilia PD2 (Ghosh and Saha 2013), Eichhornia spp. (Dave, Damani, and Tipre 2010), Micrococcus sp. and Aspergillus sp. (Congeevaram et al. 2007), Escherichia coli ASU7 (Abskharon et al. 2008), and E. coli ASU3 (Abskharon et al. 2010). However, the bioremediation ability of metal-resistant microorganisms varies, and factors such as cell structure and environmental parameters (temperature, pH, and concentration of metals and other ions) can affect their bioremediation efficiency (Hassan et al. 2018; Jaafari and Yaghmaeian 2019; Srivastava et al. 2014). To improve the heavy metal bioremediation efficiency and reduce the time and cost of the process, it is necessary to optimize the experimental factors such as temperature and solution pH (Hadiani et al. 2018). Response surface methodology (RSM) as a power statistical method can simulate the relationships between experimental factors that influence the responses.
Psychrotolerant Antarctic bacteria biosynthesize gold nanoparticles active against sulphate reducing bacteria
Published in Preparative Biochemistry & Biotechnology, 2020
Kirti Ranjan Das, Anoop Kumar Tiwari, Savita Kerkar
The GNPs produced by Antarctic Bacillus strain GL1.3 exhibited antimicrobial activity against SRB, which was determined by measuring the optical density of Desulfovibrio desulfuricans culture. Figure 3a shows the decrease in cell growth and the sulfate reducing activity of the SRB, in the presence of GNPs in the growth medium. GNP reduced the SRB number from 106 to 103cells mL−1 (decreased to 12%) and the sulfate reducing activity was reduced from 0.0246 nanomole mL−1 day−1 to 0.0016 nanomole mL−1 day−1 (decreased to 7%). The minimum inhibitory concentration (MIC) of GNP for SRB was estimated as per Zarasvand and Rai,[25] detected 200 µg mL−1 concentrations as the MIC value for the tested SRB (Figure 3b). In SEM analysis (Supplementary Figure S4) it was observed that the GNPs adhere to the SRB cells but any deterioration was not observed.
Mini review on nanoimmobilization of lipase and cellulase for biofuel production
Published in Biofuels, 2020
Ashok Rao, A. Sathiavelu, S. Mythili
There are biological, physical and chemical processes for the production of nanoparticles. The biological method includes the reduction process, in which plant extracts are used as media for nanoparticle production. Examples include latex of Jatropha curcas, and leaf extract of Acalypha indica. Various bacteria, fungi and algae are used for the reduction-mediated nanoparticle synthesis, such as Clostridium spp., Escherichia coli, Aspergillus fumigatus, Neurospora crassa, Shewanella, Sargassum wightii and Chlorella vulgaris. By contrast, Bacillus sphaericus JG-A12, Lactobacillus spp., Enterococcus faecium, Lactococcus garvieae and Pediococcus pentosaceus use a biosorption process followed by reduction for nanoparticle synthesis. Fusarium oxysporum uses an enzyme-based method for nanoparticle production. Usually, biologically based methods produce nanoparticles of gold and silver, although there are reports of copper, cadmium, uranium, lead, arsenic, aluminum, platinum and palladium nanoparticle production from Clostridium, Bacillus sphaericus JG-A12, Escherichia coli, Desulfovibrio desulfuricans, Fusarium oxysporum, Neurospora crassa and Shewanella. The mechanism for green synthesis of nanoparticles is based on reductase, and sometimes structural proteins, amino acids, polysaccharides, polyphenols, terpenoids and organic acids also play the role of reductase. The Nicotinamide Adenine Dinucleotide Hydrogen (NADH)-dependent reductase plays an important role in the synthesis of nanoparticles. The biogenic nanoparticles may be of single metal or bimetallic or salt form (CdS). Nanoparticle biosynthesis may be intracellular, extracellular or on membranes. Cell supernatants are used for extracellular nanoparticle synthesis, whereas for intracellular synthesis of nanoparticles, cultured biomass is used. The current trend uses extracellular nanoparticle synthesis as it reduces the number of steps in the downstream process. The synthesis of uniform-sized nanoparticles from plant extract requires optimum salt concentration, pH value, temperature, aeration, incubation period, mixing ratio of extract and metal salt. Nanoparticle synthesis by plant extract is more cost-effective than microbe-based nanoparticle synthesis; however, microbe-based nanoparticle synthesis can be controlled more easily than plant-based nanoparticle synthesis. The advantage of green synthesis of nanoparticles is its biocompatibility, as the biogenic nanoparticles have a biocompatible cap of biologically active sites which further enhances the usability of biosynthesized nanoparticles for various processes. Second, nanoparticle production by biogenic means takes less time than physiochemical synthesis does. Third, biogenic nanoparticles have a higher tendency to form a corona while adsorbing biomolecules and encountering biological fluids. Lastly, green synthesis does not require a stabilizing agent like a biological system as biogenic nanoparticles themselves act as a stabilizing agent [21–24].